1. Field of the Invention
This invention relates to a silver halide X-ray photosensitive material for medically diagnostic use, and more particularly to a silver halide X-ray photosensitive material having a wide exposure latitude in a specific region of the characteristic curve thereof and is so sharp as to be convenient for medical diagnoses, and still more particularly to the so-called direct X-ray photographic film.
2. Description of the Prior Art
When X-ray photographing the regions of an organism with a silver halide X-ray photosensitive material (hereinafter simply called an X-ray photosensitive material), a high order of diagnosing capability is required for early finding a nidus and for avoiding a diagnostic error. However, the conventional X-ray photosensitive materials cannot always satisfy these requirements.
To be concrete, the conventional direct X-ray photosensitive materials are roughly classified into (a) a high-gamma type, (b) a low-gamma type and (c) a medium-gamma type. The high-gamma type materials are, substantially poor in the information contents in a low exposure area, though the sharpness thereof is relatively good; the low-gamma type materials (b) are, on the contrary, poor in sharpness, though the information contents in the low exposure area are aboundant, so that it is hard to diagnose; and the medium-gamma type materials (c) are merely an average in the sharpness as well as in the information contents in the low-exposure area.
On the characteristic curves drawn when the above-mentioned types of direct X-ray photosensitive materials were processed in the undermentioned processing conditions, .gamma..sub.1 and .gamma..sub.2 were obtained at the points of optical density of 0.50 and 1.50, and at the points of optical density of 0.05 and 0.30, respectively. The typical examples of the .gamma..sub.1 and .gamma..sub.2 are shown in the following Table-1: